Biology Reference
In-Depth Information
than worker larvae. In fact, by day three, the worker larvae are larger
than queen larvae, probably because they both have access to the same
quantities of food, but queens have higher metabolism. JH titers are ele-
vated in queen larvae relative to worker larvae throughout larval devel-
opment. Sugar concentration goes up in worker food at er the fourth in-
star; it is necessary for them to pupate. (An instar is a developmental
stage that is marked by a moult, the shedding and regrowing of the exter-
nal skeleton of insects. Honey bee larvae moult roughly every 24 hours.
h erefore, there is a rough correspondence between the age of larvae and
the instar [Figure 8.3].) Nurses deposit a large excess of food in queen
cells before they are capped on the i t h day (i th instar) at er hatching,
3
Ecdysteroids
h 1
JH
h 2
h 3
2
1
L1
L2
L3
L4
L5
LS
PPQ PPW
1
2
3
4
5
6
7
Age (Days)
Figure 8.3. Feeding regimes and hormonal proi les of developing queens and
workers. h e JH titers of queens (solid black line) and workers (dashed black line)
respond to the feeding regimes imposed by nurses. Ecdysteroid titers are shown
by gray lines. Queen food is unrestricted and contains about 12 percent sugar (top
bar), whereas worker food changes over development (multishaded bar). During
the i rst three instars (L1-L3) worker food is unrestricted but contains only
around 4 percent sugar. Feeding is restricted in the fourth instar, and in the i t h
the sugar content is increased. At er nurses seal the worker cells (LS), workers
starve through to the prepupal stage (PPW), whereas queen cells are mass
provisioned at sealing, so queens continue feeding until the prepupal stage (PPQ).
Ecdysteroid levels rise at er the cells are sealed, signaling the moult into the pupal
stage. From Leimar et al. 2012. “Development and evolution of caste dimorphism
in honeybees—a modeling approach,” Ecology and Evolution 2:3098-3109.
 
Search WWH ::




Custom Search